Elastic and Inelastic Electron Scattering in Hydrogen

Abstract

A study of both the energy distribution and the angular distribution of electrons scattered by hydrogen molecules was made. Elastic scattering was investigated in the range between 40° and 165°, for collision energies between 35 and 200 volts. The number of electrons scattered at any angle was smaller the greater the energy of impact. In all the curves a minimum was found between 90° and 110°, while for the 35 and 50 volt collisions the curves rose to a definite maximum at 155° to 160°. Inelastic scattering was found to occur with energy losses ranging from a minimum of about 12.0 volts, through a sharply defined most probable loss at 12.6 volts, to a complete loss of all the energy. It was found that as the energy of collision was increased the probability of the larger energy losses increased with respect to the probability of the smaller energy losses. Angular distribution curves were steeper, the smaller the amount of energy lost at collision for a given collision energy. Also, for any particular energy loss, the steepness increased with the speed of the colliding electrons. The electrons which are torn off from atoms in ionizing collisions are termed ejected electrons and are presumably those which appear in our experiment with but little or no energy. The angular distribution of the ejected electrons, having various amounts of energy (1 to 8 volts), were studied for different collision energies (35 to 340 volts). In every case there was a noteworthy absence of considerable scattering at small angles, so characteristic of the scattering of faster electrons. In many cases, pronounced peaks were found in the angular distribution curves at large angles (90° to 160°). These peaks change in position and size in a regular manner with the energy of collision and the energy of the ejected electron.